Table 2. Monthly average difference in standardized RTIs^a before and after intervention in Guangzhou, China.

Month	Pre-intervention	Post-intervention	Difference	P valueb
Jan.	81	69	12	<0.001
Feb.	67	61	6	0.006
Mar.	85	75	10	<0.001
Apr.	80	76	4	0.009
May	97	82	15	<0.001
Jun.	86	82	4	0.008
Jul.	91	84	7	<0.001
Aug.	96	82	14	0.008
Sep.	94	84	10	<0.001
Oct.	107	84	23	<0.001
Nov.	97	89	8	<0.001
Dec.	103	82	21	<0.001
Total	1085	951	134	<0.001

RTIs, road-traffic injuries.

^aRTIs were standardized as a unit of 1 million population and 1 million vehicles.

^bThe differences were examined by t test on a daily basis.